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3 years ago

How does calcium obey the octet rule when reacting to form compounds?

Chemistry

2 answers:

wolverine [178]3 years ago

8 0

The answer is C. because it gives up two electrons.

Leya [2.2K]3 years ago

5 0

Answer: Option (C) is the correct answer.

Explanation:

Atomic number of calcium is 20 and its electronic distribution is 2, 8, 8, 2.

Therefore, a calcium atom contains two valence electrons and in order to attain stability it needs to lose two electrons.

Hence, it acquires a charge of +2 as $Ca^{2+}$ by loss of two electrons.

As, according to the octet rule there must be eight electrons in the valence shell.

Thus, we can conclude that calcium obey the octet rule when reacting to form compounds as gives up electrons.

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The rate constant for the reaction 3A equals 4b is 6.00×10 how long will it take the concentration of a to drop from 0.75 to 0.2

Lelu [443]

This question is incomplete, the complete question is;

The rate constant for the reaction 3A equals 4B is 6.00 × 10⁻³ L.mol⁻¹min⁻¹.

how long will it take the concentration of A to drop from 0.75 to 0.25M ?

from the unit of the rate constant we know it is a second reaction order

OPTIONS

a) 2.2×10^−3 min

b) 5.5×10^−3 min

c) 180 min

d) 440 min

e) 5.0×10^2 min

Answer:

it will take 440 min for the concentration of A to drop from 0.75 to 0.25M

Option d) 440 min is the correct answer

Explanation:

Given that;

Rate constant K = 6.00 × 10⁻³ L.mol⁻¹min⁻¹

3A → 4B

given that it is a second reaction order;

k = 1/t [ 1/A - 1/A₀]

kt = [ 1/A - 1/A₀]

t = [ 1/A - 1/A₀] / k

K is the rate constant(6.00 × 10⁻³)

A₀ is initial concentration( 0.75 )

A is final concentration(0.25)

t is time required = ?

so we substitute our values into the equation

t = [ (1/0.25) - (1/0.75)] / (6.00 × 10⁻³)

t = 2.6666 / (6.00 × 10⁻³)

t = 444.34 ≈ 440 min {significant figures}

Therefore it will take 440 min for the concentration of A to drop from 0.75 to 0.25M

Option d) 440 min is the correct answer

6 0

3 years ago

A penny has a mass of 2.50g and the Moon has a mass of ×7.351022kg, How many moles of pennies have a mass equal to the mass of t

baherus [9]

Answer: 122 moles

Procedure:

1) Convert all the units to the same unit

2) mass of a penny = 2.50 g

3) mass of the Moon = 7.35 * 10^22 kg (I had to arrage your numbers because it was wrong).

=> 7.35 * 10^22 kg * 1000 g / kg = 7.35 * 10^ 25 g.

4) find how many times the mass of a penny is contained in the mass of the Moon.

You have to divide the mass of the Moon by the mass of a penny

7.35 * 10^ 25 g / 2.50 g = 2.94 * 10^25 pennies

That means that 2.94 * 10^ 25 pennies have the mass of the Moon, which you can check by mulitiplying the mass of one penny times the number ob pennies: 2.50 g * 2.94 * 10^25 = 7.35 * 10^25.

5) Convert the number of pennies into mole unit. That is using Avogadros's number: 6.022 * 10^ 23

7.35 * 10^ 25 penny * 1 mol / (6.022 * 10^ 23 penny) = 1.22* 10^ 2 mole = 122 mol.

Answer: 122 mol

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3 years ago

What answer giving brainliest tysm

monitta

Answer:

Explanation:

it is repeating

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3 years ago

1)Define potential Energy.

Margarita [4]

1. Potential Energy is stored energy a object has when it's not moving.

2. Potential Energy is it's highest on the first stage because as you see the roller coaster is bout to go down the tract which is going to higher the kinetic energy and lower the potential energy.

3. Kinetic Energy is the amount of energy a object has when it's in motion or moving.

4. Kinetic Energy is it's highest in the third stage after it's gone down the tract and potential energy fully decreased and it's at zero.

Remember that potential energy is stored energy so when a object is not moving in this case the roller coaster isn't moving on the first stage when its bout to go down the roller coaster. Kinetic energy is the amount of energy a object has when it's in motion so in this case the third stage would have the highest example of Kinetic energy because it's fully in motion and has no potential energy.

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3 years ago

Ce<br>Which Computer Program enables a user to surf<br>the internet<br>Surf

Nata [24]

Answer:

Search engine. Example - Google. Hope this helps and please mark as the brainliest

Explanation:

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3 years ago